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Effect of irradiation on the antioxidative and antigenotoxic activities of a green tea leaf and stem extract
Author(s) -
Jo Cheorun,
Jeong SeokMoon,
Kim SooYeon,
Park Eunju,
Lee SeungCheol
Publication year - 2008
Publication title -
international journal of food science and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.831
H-Index - 96
eISSN - 1365-2621
pISSN - 0950-5423
DOI - 10.1111/j.1365-2621.2006.01452.x
Subject(s) - chemistry , dpph , hydrogen peroxide , camellia sinensis , antioxidant , comet assay , irradiation , food science , green tea , dna damage , ingredient , traditional medicine , biochemistry , botany , dna , biology , medicine , physics , nuclear physics
Summary Green tea ( Camellia sinensis ) leaf and stem extract, a major byproduct of the green tea industry, was investigated for its antioxidative and antigenotoxic activities after 20 kGy of irradiation. In vitro antioxidative activities, including 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) radical scavenging, hydrogen peroxide inhibition, tyrosinase inhibition activities, and the reducing power were tested. Green tea leaf extract (GTLE) had higher antioxidative activities than the green tea stem extract (GTSE). Irradiation of 20 kGy to GTLE showed a decreasing tendency in DPPH radical, hydrogen peroxide‐scavenging activities, and reducing power, while that to GTSE showed an increasing tendency of the antioxidative activities. Tyrosinase inhibition activity showed no difference on irradiation, in GTLE and GTSE. Overall, irradiation had positive influences on the antioxidative activity in the GTSE more than in the GTLE. Antigenotoxic effect of the green tea extracts on an oxidative DNA damage in human leucocytes by a DNA comet assay also indicated a protective effect of GTLE. The irradiated GTLE began to decrease the DNA damage significantly at 10 μ g mL −1 , which showed a higher inhibition activity than the non‐irradiated GTLE. The non‐irradiated and irradiated GTSE showed similar inhibition trends and they were comparable with that of the GTLE. Results suggest that the extract of GTSE, a major byproduct of the green tea industry, can be considered as a cost‐effective functional ingredient for industrial applications. Furthermore, irradiation of the GTSE may have beneficial effects on its functional activity.